1. Field of the Invention
The invention relates to a zoom lens, and in particular, to zoom lens applied to miniaturized electronic devices.
2. Description of the Related Art
With technological progress, portable electronic devices, such as notebooks, mobile phones, personal digital assistances (PDAs) or portable projectors, are being integrated with optoelectronic technology. For example, a mobile phone may be integrated with optical lenses to form a camera phone. Camera phones not only require fine image quality, but also a relatively small size and low cost.
For miniaturization of lenses and low cost, aspheric lenses are usually selected for portable electronic devices with optoelectronic technology, as a preferred lens. The aspheric lenses are utilized to eliminate spherical aberration produced by spherical lenses. In addition, a single aspheric lens can replace multiple spherical lenses to compensate for aberration, and further simplify the optical design within the lenses, reducing size and weight of the lenses. However, further miniaturization of aspheric lenses has been limited, especially for lens requiring a wide zoom range.
In Japanese Patent No. 3742645, the storage length of a collapsible lens can be further shortened by shifting a portion of the zoom lens in an optical direction. Meanwhile, in Japanese Laid-Open No. 2004-341154, instead of shifting the lens groups, the cam barrel for extending the lenses is designed to be shortened.
Although methods for miniaturizing the zoom lens have been disclosed by various publications, the eccentricity of lenses when the zoom lens is in operation has not been satisfactorily dealt with. Therefore, a method for minimizing the zoom lens is required to avoid the eccentricity of lenses when the zoom lens is in operation.